U.S. patent application number 11/504893 was filed with the patent office on 2007-04-19 for pedestrian protection apparatus, and method of tuning load characteristic of the apparatus.
This patent application is currently assigned to Kojima Press Industry Co., Ltd.. Invention is credited to Masanobu Fukukawa, Kuniaki Hasegawa, Kaoru Itou, Hiroki Kurokawa, Yoshihiro Ogura.
Application Number | 20070085356 11/504893 |
Document ID | / |
Family ID | 37660520 |
Filed Date | 2007-04-19 |
United States Patent
Application |
20070085356 |
Kind Code |
A1 |
Itou; Kaoru ; et
al. |
April 19, 2007 |
Pedestrian protection apparatus, and method of tuning load
characteristic of the apparatus
Abstract
In a pedestrian protection apparatus installed in a lower part
of a front of a vehicle, a plate extends in a longitudinal
direction of the vehicle, and includes a front section having at
least a portion protruding from the front of the vehicle, a rear
section fixed to the vehicle, and a center section provided between
the front and rear sections. The front section is more rigid than
the rear section, and the center section is less rigid than the
front section and more rigid than the rear section.
Inventors: |
Itou; Kaoru; (Nisshin-Shi,
JP) ; Ogura; Yoshihiro; (Toyota-Shi, JP) ;
Hasegawa; Kuniaki; (Kariya-Shi, JP) ; Fukukawa;
Masanobu; (Toyota-Shi, JP) ; Kurokawa; Hiroki;
(Toyota-Shi, JP) |
Correspondence
Address: |
BURR & BROWN
PO BOX 7068
SYRACUSE
NY
13261-7068
US
|
Assignee: |
Kojima Press Industry Co.,
Ltd.
Toyota-Shi
JP
|
Family ID: |
37660520 |
Appl. No.: |
11/504893 |
Filed: |
August 16, 2006 |
Current U.S.
Class: |
293/120 |
Current CPC
Class: |
B60R 2021/343 20130101;
B60R 21/34 20130101 |
Class at
Publication: |
293/120 |
International
Class: |
B60R 19/18 20060101
B60R019/18 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 19, 2005 |
JP |
2005-304726 |
Claims
1. A pedestrian protection apparatus for a vehicle comprising: a
synthetic resin plate mounted in a lower part of a front side of a
vehicle and extending in a longitudinal direction of the vehicle,
the plate including a front section having at least a protruding
portion protruding from the front side of the vehicle, a rear
section fixed to the vehicle, and a center section provided between
the front and rear sections, wherein the protruding portion of the
front section of the plate comes into contact with and sweeps away
a lower part of a leg of a pedestrian to protect the leg when the
front side of the vehicle collides with the leg, and wherein the
front section of the plate is more rigid than the rear section, and
the center section is less rigid than the front section and more
rigid than the rear section.
2. The pedestrian protection apparatus according to claim 1,
wherein the center section of the plate includes a plurality of
areas having mutually different rigidities, and the areas extend
over a full dimension of the vehicle in a transverse direction,
adjoin in the longitudinal direction of the vehicle, and are
arranged in decreasing order of the rigidities from a front side of
the center section.
3. The pedestrian protection apparatus according to claim 1,
wherein a plurality of reinforcing ribs extending in the
longitudinal direction of the vehicle are provided integrally with
each of the front and center sections of the plate so as to be
spaced in the transverse direction of the vehicle, and the front
and center sections are more rigid than the rear section in which
the reinforcing ribs are not provided, and wherein the number of
the reinforcing ribs provided in the front section is larger than
the number of the reinforcing ribs provided in the center section,
and the interval between the reinforcing ribs of the front section
in the transverse direction of the vehicle is shorter than the
interval between the reinforcing ribs of the center section so that
the front section is more rigid than the center section.
4. The pedestrian protection apparatus according to claim 1,
wherein the center section of the plate is thicker than the rear
section so that the center section is more rigid than the rear
section, and the front section is thicker than the center section
so that the front section is more rigid than the center
section.
5. The pedestrian protection apparatus according to claim 1,
wherein a first plate-shaped reinforcing member having a
predetermined rigidity is fixed on at least one surface of the
center section so that the center section is more rigid than the
rear section, and a second plate-shaped reinforcing member which is
more rigid than the first plate-shaped reinforcing member is fixed
on at least one surface of the front section so that the front
section is more rigid than the center section on which the first
plate-shaped reinforcing member is fixed.
6. A method of tuning a load characteristic of a pedestrian
protection apparatus for a vehicle, wherein the pedestrian
protection apparatus comprises: a synthetic resin plate mounted in
a lower part of a front side of a vehicle and extending in a
longitudinal direction of the vehicle, the plate including a front
section having at least a protruding portion protruding from the
front side of the vehicle, a rear section having a fixed portion
fixed to the vehicle, and a center section provided between the
front and rear sections, wherein the protruding portion of the
front section of the plate comes into contact with and sweeps away
a lower part of a leg of a pedestrian to protect the leg when the
front of the vehicle collides with the leg, wherein the front
section of the plate is more rigid than the rear section, and the
center section is less rigid than the front section and more rigid
than the rear section so that the plate is bent at a boundary
portion between the center section and the rear section and at a
front adjacent portion of the rear section on the front side of and
adjacent to the fixed portion by an impact load which is inputted
when the protruding portion of the front section comes into contact
with the leg of the pedestrian, and wherein a maximum value of the
impact load is adjusted and the load characteristic is tuned by
arbitrarily changing the dimension of the center section in the
longitudinal direction of the vehicle so as to change the distance
between the boundary portion and the front adjacent portion.
7. A method of tuning a load characteristic of a pedestrian
protection apparatus for a vehicle, wherein the pedestrian
protection apparatus comprises: a synthetic resin plate mounted in
a lower part of a front side of a vehicle and extending in a
longitudinal direction of the vehicle, the plate including a front
section having at least a protruding portion protruded from the
front side of the vehicle, a rear section having a fixed portion
fixed to the vehicle, and a center section provided between the
front and rear sections, wherein the protruding portion of the
front section of the plate comes into contact with and sweeps away
a lower part of a leg of a pedestrian to protect the leg when the
front side of the vehicle collides with the leg, wherein the front
section of the plate is more rigid than the rear section, and the
center section is less rigid than the front section and more rigid
than the rear section so that the plate is bent at a boundary
portion between the center section and the rear section and at a
front adjacent portion of the rear section on the front side of and
adjacent to the fixed portion by an impact load which is inputted
when the protruding portion of the front section comes into contact
with the leg of the pedestrian, and wherein a maximum value of the
impact load is adjusted and the load characteristic is tuned by
fixing a first plate-shaped reinforcing member to the boundary
portion and fixing a second plate-shaped reinforcing member to the
front adjacent portion, the first reinforcing member increasing a
rigidity of the boundary portion within a range below that of the
front section, and the second reinforcing member increasing a
rigidity of the front adjacent portion within a range below that of
the center section.
8. The method according to claim 6, wherein the center section of
the plate includes a plurality of areas having mutually different
rigidities, and the areas extend over a full dimension of the
vehicle in a transverse direction, adjoin in the longitudinal
direction of the vehicle, and are arranged in decreasing order of
the rigidities from a front side of the center section.
Description
[0001] The present application is based on Japanese Patent
Application No. 2005-304726 filed on Oct. 19, 2005, the contents of
which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a pedestrian protection
apparatus, and a method of tuning a load characteristic of the
apparatus. More particularly, the present invention relates to an
improved configuration of a pedestrian protection apparatus that is
installed on a lower front side of a vehicle and that protects the
legs of a pedestrian by sweeping the legs in contact with lower
parts of the legs when the front of the vehicle collides with or
comes into contact with the legs, and to a method of advantageously
tuning a load characteristic of the apparatus.
[0004] 2. Description of the Related Art
[0005] Various types of protection apparatuses are conventionally
installed on front, rear, or side faces of vehicles, such as
automobiles, mainly in order to absorb a shock energy caused in a
collision and to thereby protect the body of the vehicles and
passengers. In recent years, apparatuses for protecting a
pedestrian have been installed at the fronts of vehicles to protect
the pedestrian when the front of the vehicles collide (comes into
contact) with the pedestrian.
[0006] A so-called leg sweep member is a known pedestrian
protection apparatus. The leg sweep member is installed inside or
below a front bumper independently, and applies a reaction force to
an impact load, which is inputted in a collision between the
pedestrian and the front of the vehicle, to the lower parts of the
legs of the pedestrian so that the lower parts of the legs are
swept away (tripped) and the pedestrian falls down onto the
vehicle. This advantageously reduces the angle of forced bending of
the knees in an undesirable direction caused by the collision,
minimizes the occurrence of injuries such as a bone fracture of a
knee, and achieves protection and safety of the pedestrian.
[0007] For example, JP-A-2001-277963 discloses a leg sweep member
in which a resin foam member and a beam are mounted in the lower
part of the front of a vehicle. The resin foam member extends in a
width direction of the vehicle such that at least a part thereof
protrudes from the front of the vehicle, and the beam extends in
the width direction of the vehicle and is in contact with the rear
side of the resin foam member. JP-A-2004-25976 discloses a leg
sweep member that is formed of, for example, a metal pipe, and that
is fixed to the lower part of the front of a vehicle such as to
extend in the width direction of the vehicle. However, both the leg
sweep members disclosed in the above publications have
disadvantages to be overcome. That is, in the former pedestrian
protection apparatus including the resin foam member and the beam,
the number of components is large. For this reason, the component
cost is high, and it is troublesome to mount the apparatus. In
contrast, in the latter pedestrian protection apparatus formed of a
metal pipe, the weight thereof is inevitably high, and it is
difficult to form the apparatus in a shape that conforms to the
shape of the front of the vehicle.
[0008] In view of these circumstances, JP-A-2004-203183 proposes a
pedestrian protection apparatus including a synthetic resin plate.
The synthetic resin plate is fixed at a rear section to a vehicle
such as to extend in the longitudinal direction of the vehicle and
such that at least a portion of a front section thereof protrudes
from the front of the vehicle. When the front of the vehicle
collides with a pedestrian, the projecting portion of the front
section protruding from the front of the vehicle comes into contact
with lower parts of the legs of the pedestrian, and sweeps the legs
away. In this known pedestrian protection apparatus, a plurality of
flat ribs are disposed on one surface of the front section of the
plate and formed in a lattice, and therefore, a high rigidity of
the front section is ensured. Moreover, a section of the plate
other than the front section is shaped like a flat plate extending
in the longitudinal direction of the vehicle with a sufficient
length so that the front section can protrude from the front of the
vehicle.
[0009] In the pedestrian protection apparatus having the
above-described configuration, the number of components is small.
Moreover, since the plate, which partly protrudes from the front of
the vehicle, is formed of easily formable synthetic resin, the
pedestrian can be protected while effectively overcoming the
disadvantages of the apparatus including the resin foam member and
the beam, and the apparatus formed of a metal pipe. In addition,
since the front section of the plate is highly rigid, it is
prevented from being deformed by a shock caused by the contact with
the legs of the pedestrian, or the amount of deformation is
sufficiently reduced. Therefore, a reaction force to the impact
load inputted to the plate efficiently acts on the legs of the
pedestrian via the front section.
[0010] However, as the result of various tests and investigations,
the present inventors found that the maximum value of the impact
load inputted when the front section of the synthetic resin plate
in the above pedestrian protection apparatus collided with the legs
of a pedestrian did sometimes not reach a target value, that a
reaction force required to sweep the legs away in the collision
could not be ensured in this case, and that protection of the legs
was insufficient.
[0011] In general, in a pedestrian protection apparatus installed
at the front of the vehicle, the load characteristic is required to
vary depending on the type of the vehicle, for example, to be
optimized in accordance with the shape of the front of the vehicle
and a shock-absorbing member of a front bumper mounted at the front
of the vehicle together with the pedestrian protection apparatus so
that a reaction force to an impact load applied in a collision
between the legs of a pedestrian and the front of the vehicle
sufficiently acts on the legs to reliably sweep the legs away,
regardless of the type of the vehicle in which the apparatus is
installed. However, in the known pedestrian protection apparatus
having the above-described configuration, it is difficult to tune
the load characteristic, so that it is difficult to optimize the
same.
FEATURES OF THE INVENTION
[0012] The present invention has been made in view of the
above-described circumstances, and an object of the invention is to
provide a pedestrian protection apparatus that reliably sweeps away
and sufficiently protects legs of a pedestrian with which the front
of a vehicle collides. Another object of the invention is to
provide a method of tuning a load characteristic that can easily
and reliably optimize the load characteristic of the pedestrian
protection apparatus.
[0013] In order to overcome the above-described problems, the
present inventors conducted a pedestrian collision test under the
assumption that the front of a vehicle collided with the legs of
the pedestrian. In this test, a test vehicle including the
above-described known pedestrian protection apparatus having a
synthetic resin plate was used. As a result of the test,
deformation of a front section of the plate having high rigidity
was prevented, or the amount of deformation was minimized in a
collision with the leg of the pedestrian, as described above.
However, since a remaining section of the plate other than the
front section was shaped like a simple flat plate, and is
relatively long in the longitudinal direction of the vehicle, the
plate was bent (buckled) at a center portion in a length direction
(longitudinal direction of the vehicle) corresponding to a
shock-receiving direction, in which the shock is primarily applied
to the apparatus. Furthermore, as for the load characteristic of
the known apparatus, the pedestrian collision test also revealed
that the amount of increase of the impact load per unit time in the
early stage of the shock input was relatively small.
[0014] From the above facts, the present inventors made the
following assumption. That is, when the front section of the plate
in the known apparatus comes into contact with the legs of the
pedestrian, the remaining section of the plate other than the front
section is bent in an approximate V-shape, and therefore, the
pedestrian protection apparatus provides a load characteristic such
that the impact load gently increases in the early stage of the
shock input, that is, such that much time is required for the
impact load to reach a target load. For this reason, the maximum
value of the impact load sometimes does not reach the target value
in the known pedestrian protection apparatus.
[0015] Accordingly, the present inventors earnestly studied the
relationship between deformation of the remaining section of the
plate other than the front section having high rigidity, and the
load characteristic. As a result of the study, the present
inventors found that the impact load could be rapidly increased in
the early stage of the shock input in a collision between the front
of the vehicle and the legs of the pedestrian by bending
(buckling), by the input shock, the remaining section of the plate
at two points spaced with a predetermined distance therebetween in
the longitudinal direction corresponding to the shock-receiving
direction (longitudinal direction of the vehicle) so that the plate
is bent in an approximate S-shape or a staircase shape. Through
further various tests and investigations, the present inventors
also found that the remaining section of the plate was deformed to
be bent in an approximate S-shape or in a staircase form by the
input shock when the remaining section included portions that had
mutually different rigidities and that were arranged in a specific
order.
[0016] The present invention has been completed on the basis of the
above findings. The principle of the present invention is to
provide a pedestrian protection apparatus, which includes a
synthetic resin plate mounted in a lower part of a front side of a
vehicle and extending in a longitudinal direction of the vehicle.
The plate includes a front section having at least a protruding
portion protruding from the front side of the vehicle, a rear
section fixed to the vehicle, and a center section provided between
the front and rear sections. The protruding portion of the front
section of the plate comes into contact with and sweeps away a
lower part of a leg of a pedestrian to protect the leg when the
front side of the vehicle collides with the leg. The front section
of the plate is more rigid than the rear section, and the center
section is less rigid than the front section and more rigid than
the rear section.
[0017] In the pedestrian protection apparatus according to the
present invention, when the front side of the vehicle collides with
the pedestrian, the front section of the synthetic resin plate
extending in the longitudinal direction of the vehicle comes into
contact with the leg of the pedestrian. The front section is more
rigid than the other sections of the plate. The other sections
include the rear section having the portion fixed to the vehicle
and is less rigid than the other sections of the plate, and the
center section which is more rigid than the rear section.
[0018] For this reason, when a shock is inputted by a collision
between the leg of the pedestrian and the front side of the
vehicle, stress concentration is caused in a boundary portion
between the center and rear sections of the plate, and in a front
adjacent portion of the rear section that is on the front side and
adjacent to a portion fixed to the vehicle. Therefore, the plate is
bent (buckled) at two positions, that is, the boundary portion and
the front adjacent portion so as to be in an approximate S-shape or
a staircase shape, and the impact load is rapidly increased in the
early stage of the shock input. As a result, the maximum value of
the input load inputted by the collision between the leg of the
pedestrian and the front of the vehicle can speedily and reliably
reach a target value, and a reaction force to the impact load can
be ensured sufficiently and reliably.
[0019] Therefore, in the pedestrian protection apparatus of the
present invention, a reaction force to the impact load inputted in
a collision between the leg and the front of the vehicle
sufficiently acts on the leg. This allows the leg to be reliably
swept away and to be sufficiently protected at a higher level.
[0020] For example, by increasing or decreasing the dimension of
the center section of the plate in the longitudinal direction of
the vehicle, the distance between the boundary portion between the
center and rear sections, and the front adjacent portion on the
front side of and adjacent to the portion of the rear section fixed
to the vehicle, in other words, the distance between the portions
that are bent when a shock is inputted in a collision between the
leg of the pedestrian and the front of the vehicle can be changed
arbitrarily. Consequently, it is possible to adjust the amount of
increase of the impact load in the early stage of the shock input.
For example, the amount of increase of the impact load can be
decreased by increasing the distance between the boundary portion
and the front adjacent portion, and can be increased by decreasing
the distance.
[0021] Therefore, the load characteristic can be arbitrarily
changed by simply changing the dimension of the center section of
the plate in the longitudinal direction of the vehicle. As a
result, even when the required characteristic varies depending on
the type of the vehicle in which the apparatus is installed, it is
possible to easily correspond to the variation.
[0022] The present invention is preferably practiced in at least
the following features.
[0023] (1) A pedestrian protection apparatus for a vehicle
comprising:
[0024] a synthetic resin plate mounted in a lower part of a front
side of a vehicle and extending in a longitudinal direction of the
vehicle, the plate including a front section having at least a
protruding portion protruding from the front side of the vehicle, a
rear section fixed to the vehicle, and a center section provided
between the front and rear sections,
[0025] wherein the protruding portion of the front section of the
plate comes into contact with and sweeps away a lower part of a leg
of a pedestrian to protect the leg when the front side of the
vehicle collides with the leg, and
[0026] wherein the front section of the plate is more rigid than
the rear section, and the center section is less rigid than the
front section and more rigid than the rear section.
[0027] (2) The pedestrian protection apparatus according to the
above feature (1), wherein the center section of the plate includes
a plurality of areas having mutually different rigidities, and the
areas extend over a full dimension of the vehicle in a transverse
direction, adjoin in the longitudinal direction of the vehicle, and
are arranged in decreasing order of the rigidities from a front
side of the center section. According to this feature, when a shock
is inputted by a collision between the leg of the pedestrian and
the front of the vehicle, the plate can also be bent at a boundary
portion between the areas having mutually different rigidities in
the center section, depending on the volume of the shock. This can
effectively suppress an excessive increase of the shock load in the
early stage of the shock input.
[0028] The pedestrian protection apparatus according to the above
feature (1) or (2),
[0029] wherein a plurality of reinforcing ribs extending in the
longitudinal direction of the vehicle are provided integrally with
each of the front and center sections of the plate so as to be
spaced in the transverse direction of the vehicle, and the front
and center sections are more rigid than the rear section in which
the reinforcing ribs are not provided, and
[0030] wherein the number of the reinforcing ribs provided in the
front section is larger than the number of the reinforcing ribs
provided in the center section, and the interval between the
reinforcing ribs of the front section in the transverse direction
of the vehicle is shorter than the interval between the reinforcing
ribs of the center section so that the front section is more rigid
than the center section. In this case, for example, the rigidities
of the front section and the center section can be made different
from each other without fixing separate members onto the front
section and the center section. Consequently, the plate including
the sections having different rigidities, and the entire device can
be advantageously configured with a minimized number of
components.
[0031] (4) The pedestrian protection apparatus according to the
above feature (1) or (2), wherein the center section of the plate
is thicker than the rear section so that the center section is more
rigid than the rear section, and the front section is thicker than
the center section so that the front section is more rigid than the
center section. According to this feature, the plate including the
sections having different rigidities, and the entire device can
also be advantageously configured with a minimized number of
components.
[0032] (5) The pedestrian protection apparatus according to the
above feature (1) or (2), wherein a first plate-shaped reinforcing
member having a predetermined rigidity is fixed on at least one
surface of the center section so that the center section is more
rigid than the rear section, and a second plate-shaped reinforcing
member which is more rigid than the first plate-shaped reinforcing
member is fixed on at least one surface of the front section so
that the front section is more rigid than the center section on
which the first plate-shaped reinforcing member is fixed. According
to this feature, the plate itself can be formed of a simple flat
plate having a uniform rigidity, and the plate can be designed
easily.
[0033] (6) A method of tuning a load characteristic of a pedestrian
protection apparatus for a vehicle,
[0034] wherein the pedestrian protection apparatus comprises:
[0035] a synthetic resin plate mounted in a lower part of a front
side of a vehicle and extending in a longitudinal direction of the
vehicle, the plate including a front section having at least a
protruding portion protruding from the front side of the vehicle, a
rear section having a fixed portion fixed to the vehicle, and a
center section provided between the front and rear sections,
[0036] wherein the protruding portion of the front section of the
plate comes into contact with and sweeps away a lower part of a leg
of a pedestrian to protect the leg when the front of the vehicle
collides with the leg,
[0037] wherein the front section of the plate is more rigid than
the rear section, and the center section is less rigid than the
front section and more rigid than the rear section so that the
plate is bent at a boundary portion between the center section and
the rear section and at a front adjacent portion of the rear
section on the front side of and adjacent to the fixed portion by
an impact load which is inputted when the protruding portion of the
front section comes into contact with the leg of the pedestrian,
and
[0038] wherein a maximum value of the impact load is adjusted and
the load characteristic is tuned by arbitrarily changing the
dimension of the center section in the longitudinal direction of
the vehicle so as to change the distance between the boundary
portion and the front adjacent portion.
[0039] According to this feature, for example, even when various
load characteristics are required, depending on the shape of the
front of the vehicle and a shock-absorbing member of a front bumper
installed at the front side of the vehicle together with the
pedestrian protection apparatus, the load characteristic can be
easily tuned by arbitrarily changing the maximum value of the
impact load by means of an extremely simple design change, that is,
by simply changing the dimension of the center section of the plate
in the longitudinal direction of the vehicle.
[0040] Therefore, the load characteristic of the pedestrian
protection apparatus can be optimized easily and reliably. As a
result, when the front of the vehicle collides with the leg of the
pedestrian, a reaction force to the impact load can sufficiently
act on the leg, and the leg can be reliably swept away, regardless
of the type of the vehicle in which the apparatus is installed.
[0041] (7) A method of tuning a load characteristic of a pedestrian
protection apparatus for a vehicle,
[0042] wherein the pedestrian protection apparatus comprises:
[0043] a synthetic resin plate mounted in a lower part of a front
side of a vehicle and extending in a longitudinal direction of the
vehicle, the plate including a front section having at least a
protruding portion protruded from the front side of the vehicle, a
rear section having a fixed portion fixed to the vehicle, and a
center section provided between the front and rear sections,
[0044] wherein the protruding portion of the front section of the
plate comes into contact with and sweeps away a lower part of a leg
of a pedestrian to protect the leg when the front side of the
vehicle collides with the leg,
[0045] wherein the front section of the plate is more rigid than
the rear section, and the center section is less rigid than the
front section and more rigid than the rear section so that the
plate is bent at a boundary portion between the center section and
the rear section and at a front adjacent portion of the rear
section on the front side of and adjacent to the fixed portion by
an impact load which is inputted when the protruding portion of the
front section comes into contact with the leg of the pedestrian,
and
[0046] wherein a maximum value of the impact load is adjusted and
the load characteristic is tuned by fixing a first reinforcing
member to the boundary portion and fixing a second reinforcing
member to the front adjacent portion, the first reinforcing member
increasing a rigidity of the boundary portion within a range below
that of the front section, and the second reinforcing member
increasing a rigidity of the front adjacent portion within a range
below that of the center section.
[0047] According to this feature, for example, even when various
load characteristics are required, depending on the shape of the
front of the vehicle and a shock-absorbing member of a front bumper
installed at the front of the vehicle together with the pedestrian
protection apparatus, the flexural elastic constants and flexural
strengths of the boundary portion and the front adjacent portion
can be appropriately changed by an extremely simple design change,
that is, by simply fixing the first reinforcing member and the
second reinforcing member to the boundary portion and the front
adjacent portion. Consequently, it is possible to arbitrarily
change the maximum value of the impact load and to easily tune the
load characteristic.
[0048] Therefore, the tuning method according to this feature can
effectively achieve operations and advantages similar to those
achieved by the above-described feature (6).
[0049] (8) The method according to the above feature (6) or (7),
wherein the center section of the plate includes a plurality of
areas having mutually different rigidities, and the areas extend
over a full dimension of the vehicle in a transverse direction,
adjoin in the longitudinal direction of the vehicle, and are
arranged in decreasing order of the rigidities from a front side of
the center section. According to this feature, when a shock is
inputted by a collision between the leg of the pedestrian and the
front of the vehicle, the plate can also be bent at a boundary
portion between the areas having mutually different rigidities in
the center section, depending on the volume of the shock. This can
effectively suppress an excessive increase of the impact load in
the early stage of the shock input. Moreover, the load
characteristic can be tuned more accurately.
BRIEF DESCRIPTION OF THE DRAWINGS
[0050] The above and other objects, features, advantages and
technical and industrial significance of the present invention will
be better understood by reading the following detailed description
of presently preferred embodiments of the invention, when
considered in connection with the accompanying drawings, in
which:
[0051] FIG. 1 is an explanatory top view a pedestrian protection
apparatus according to a first embodiment of the present
invention;
[0052] FIG. 2 is a cross-sectional view, taken along line 2-2 of
FIG. 1;
[0053] FIG. 3 is an explanatory bottom view of the pedestrian
protection apparatus shown in FIG. 1;
[0054] FIG. 4 is an explanatory view showing a state in which the
pedestrian protection apparatus shown in FIG. 1 is installed in a
vehicle;
[0055] FIG. 5 is an explanatory view showing a state in which the
pedestrian protection apparatus is deformed when the front of the
vehicle collides with a pedestrian;
[0056] FIG. 6 is a cross-sectional view, corresponding to FIG. 2, a
pedestrian protection apparatus according to a second embodiment of
the present invention;
[0057] FIG. 7 is an explanatory view, corresponding to FIG. 5,
showing a state in which the pedestrian protection apparatus shown
in FIG. 6 is deformed when a pedestrian collides with the front of
a vehicle in which the pedestrian protection apparatus is
installed;
[0058] FIG. 8 is a cross-sectional view, corresponding to FIG. 2, a
pedestrian protection apparatus according to a third embodiment of
the present invention;
[0059] FIG. 9 is a cross-sectional view, corresponding to FIG. 2,
of a pedestrian protection apparatus according to a fourth
embodiment of the present invention;
[0060] FIG. 10 is a cross-sectional view, corresponding to FIG. 2,
of a pedestrian protection apparatus according to a fifth
embodiment of the present invention;
[0061] FIG. 11 is a cross-sectional view, corresponding to FIG. 2,
of a pedestrian protection apparatus according to the present
invention;
[0062] FIG. 12 is a graph showing changes of impact loads with time
found in a pedestrian collision test conducted on the assumption
that a pedestrian collides with the front of a vehicle in which a
pedestrian protection apparatus having a configuration according to
the present invention is installed and in pedestrian collision
tests conducted on the assumption that the pedestrian collides with
the front of the vehicles in which pedestrian protection apparatus
having configurations different from the configuration of the
present invention are installed;
[0063] FIG. 13 is a graph showing changes of impact loads with time
found in a pedestrian collision test conducted on the assumption
that a pedestrian collides with the front of a vehicle in which a
pedestrian protection apparatus having a configuration according to
the present invention and including a base plate having a center
section that is long in the longitudinal direction is installed and
in a pedestrian collision test conducted on the assumption that the
front of a vehicle, in which a pedestrian protection apparatus
having a configuration according to the present invention and
including a base plate having a center section that is short in the
longitudinal direction is installed, collides with the
pedestrian;
[0064] FIG. 14 is a graph showing changes of impact loads with time
found in a pedestrian collision test conducted on the assumption
that the front of a vehicle, collides with a pedestrian in which a
pedestrian protection apparatus having a configuration according to
the present invention and including a reinforcing plate fixed on a
base plate so as to extend over a boundary portion and a front
adjacent portion is installed and in a pedestrian collision test
conducted on the assumption that the front of a vehicle, in which a
pedestrian protection apparatus having a configuration according to
the present invention and including a base plate having no
reinforcing plate is installed, collides with the pedestrian;
and
[0065] FIG. 15 is a graph showing changes of impact loads with time
found in a pedestrian collision test conducted on the assumption
that the front of a vehicle, in which a pedestrian protection
apparatus having a configuration according to the present invention
and including a reinforcing rib provided integrally with a base
plate so as to extend over a boundary portion and a front adjacent
portion is installed, collides with a pedestrian and in a
pedestrian collision test conducted on the assumption that the
front of a vehicle, in which a pedestrian protection apparatus
having a configuration according to the present invention and
including a base plate having no reinforcing rib is installed,
collides with the pedestrian.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0066] In order to more clearly specify the present invention,
embodiments of the invention will be described in detail below with
reference to the drawings.
[0067] FIGS. 1 and 2 are a top view and a cross-sectional view,
respectively, schematically showing a leg sweep member 10 serving
as a pedestrian protection apparatus according to a first
embodiment of the present invention. The leg sweep member 10 of the
first embodiment is installed inside a front bumper provided at the
front of an automobile, and includes a base plate 12 serving as the
plate, as shown in FIGS. 1 and 2.
[0068] More specifically, the base plate 12 is made of, for
example, a synthetic resin material such as polypropylene or ABS
resin, and is formed of a substantially rectangular thin plate. A
dimension of the base plate 12 in the breadth direction in FIG. 1,
which corresponds to the width or transverse direction of the
automobile in which the leg sweep member 10 is installed
(hereinafter referred to as the breadth direction) is smaller by a
predetermined dimension than the width of the automobile, and a
dimension thereof in the depth direction in FIG. 1, which
corresponds to the longitudinal direction of the automobile
(hereinafter referred to as the depth direction) is sufficiently
smaller than the dimension in the breadth direction. The base plate
12 has an end curved surface 14 that is curved in accordance with
the shape of an inner surface of the front bumper. The dimensions
of the base plate 12 in the breadth and depth directions are
appropriately determined, for example, depending on the width of
the automobile in which the leg sweep member 10 is installed, and
the size of the installation space. For example, the dimension in
the-depth direction is set at approximately 80 to 200 mm, and the
thickness is generally set at approximately 3 mm.
[0069] A plurality of (twelve in the first embodiment) first ribs
16 having the same height and shaped like a thin flat plate
protrude integrally from an upper surface of the base plate 12. The
first ribs 16 extend straight and rearward at a constant height
from the side of the end curved surface 14. The first ribs 16 are
arranged at regular intervals in the breadth direction. A third rib
18 shaped like a thin flat plate also protrudes integrally at
almost the center in the depth direction on the upper surface of
the base plate 12. The third rib 18 extends straight at a constant
height over almost the full dimension of the base plate 12 in the
breadth direction, and is combined with each of the first ribs 16
in the form of a cross.
[0070] The interval between the first ribs 16 is, for example,
approximately 25 mm. The height and thickness of the first ribs 16
are approximately 25 mm and approximately 3 mm, respectively. The
dimension of the first ribs 16 is about three-fourths of the
dimension of the base plate 12 in the depth direction. The height
and thickness of the third rib 18 are substantially equal to those
of the first ribs 16.
[0071] A plurality of (four in the first embodiment) fourth ribs 20
having a predetermined dimension protrudes integrally from a front
end of the upper surface of the base plate 12. The fourth ribs 20
extend in the depth direction, and are arranged in line along the
end curved surface 14. Each of the fourth ribs 20 connects front
ends of some (three in the first embodiment) of the first ribs 16.
The fourth ribs 20 are shaped like a thin flat plate, and the
height and thickness thereof are substantially equal to those of
the first ribs 16 and the third rib 18.
[0072] A fifth rib 22 is provided a predetermined distance behind
the fourth ribs 20 on the upper surface of the base plate 12. The
fifth rib 22 projects at a predetermined height, and extends over
almost the full dimension of the base plate 12 in the breadth
direction. That is, at a position offset rearward from the end
curved surface 14a of the base plate 12 by a distance corresponding
to about one-fourth of the dimension of the base plate 12 in the
depth direction, the fifth rib 22 extends across a front part of
the base plate 12, and crosses all the first ribs 16. A front side
face of the fifth rib 22 faces rear side faces of the fourth ribs
20 with a predetermined space therebetween. Unlike the first ribs
16 and the third and fourth ribs 18 and 20 that are each shaped
like a thin flat plate, the fifth rib 22 is formed by bending a
rear portion of the front part of the upper surface of the base
plate 12 so that the fifth rib 22 is open downward and is angularly
U-shaped in cross section.
[0073] Second ribs 24 are provided integrally from the upper
surface of the base plate 12 between the fourth ribs 20 and the
fifth rib 22 that face each other. The second ribs 24 extend
straight in the longitudinal direction from rear side faces of the
fourth ribs 20 to a front side face of the fifth rib 22. Each of
the second ribs 24 is provided approximately at the midpoint
between the first longitudinal ribs 16 that are adjacent to each
other in the breadth direction. That is, between the fourth ribs 20
and the fifth rib 22 that face each other on the upper surface of
the base plate 12, front portions of the first ribs 16 and the
second ribs 24 are arranged in the breadth direction at a short
interval of approximately 12.5 mm that corresponds to half the
interval between the first ribs 16. Similar to the first ribs 16
and the third and fourth ribs 18 and 20, the second ribs 24 are
each shaped like a thin flat plate, and have a height and a
thickness substantially equal to those of the ribs 16, 18, and
20.
[0074] In this way, the first ribs 16, the second ribs 24, the
fourth ribs 20, and the fifth rib 22 are provided integrally from a
front section 26 of the base plate 12 so that the ribs are combined
in a lattice form. The area of the front section 26 is about
one-fourth of the total area of the upper surface of the base plate
12. On a rear section 28 whose area is about one-fourth of the
total area of the upper surface of the base plate 12, projections,
such as ribs, are not provided, and an upper surface of the rear
section 28 is flat. On a center section 30 whose area is about a
half of the total area of the upper surface of the base plate 12,
remaining portions of the first ribs 16 other than the front
portions, and the third rib 18 are integrally provided so that each
of the remaining portions crosses the third rib 18.
[0075] Accordingly, in the front section 26 on which the four-types
of ribs 16, 20, 22, and 24 are provided, the rigidity against a
bending load, that is, the deformation strength against an impact
load inputted in the depth direction when the leg sweep member 10
is installed in the automobile, is sufficiently higher than that of
the rear section 28 of the base plate 12 on which ribs are not
provided. Further, the center section 30 of the base plate 12, on
which a smaller number of ribs 16 and 18 are provided than on the
front section 26, is less rigid than that of the front section 26
and more rigid than the rear section 28.
[0076] As is evident from the above, in the leg sweep member 10 of
the first embodiment, the first ribs 16 and the second ribs 24
serve as reinforcing ribs, and the third, fourth, and fifth ribs
18, 20, and 22 serve as auxiliary reinforcing ribs. Since the total
dimension of the base plate 12 in the depth direction is generally
approximately 80 to 200 mm, as described above, the dimensions
(D.sub.1 and D.sub.3 in FIG. 2) in the depth direction of the front
section 26 having the highest rigidity and the rear section 28
having the lowest rigidity are each approximately 15 to 50 mm, and
the dimensions (D.sub.2 in FIG. 2) in the depth direction of the
center section 30, which is less rigid than the front section 26
and more rigid than the rear section 28, is approximately 50 to 100
mm.
[0077] As shown in FIGS. 1 to 3, a plurality of first auxiliary
ribs 32 and a second auxiliary rib 34 are also provided on lower
surfaces of the front section 26 and the center section 30 of the
base plate 12. The first and second auxiliary ribs 32 and 34 are
respectively positioned corresponding to the first ribs 16 and the
third rib 18, and have structures substantially similar to those of
the ribs 16 and 18. The number of the first auxiliary ribs 32 is
the same as that of the first ribs 16. Therefore, the rigidities of
the front section 26 and the center section 30 are further
increased as a whole. Through-holes 36 and 38 are provided in a
front end and side ends of the front section 26 of the base plate
12 and in a rear end of the rear section 28. When the leg sweep
member 10 is installed in the automobile, resin clips and fixing
bolts, which will be described below, are passed through the
through-holes 36 and 38. The through-holes 36 and 38 are arranged
at predetermined intervals in the breadth direction.
[0078] The leg sweep member 10 having the above-described
configuration is installed inside a front bumper 40 provided at the
front of the automobile, for example, in a manner shown in FIG. 4.
The front bumper 40 has a bumper cover 46 including an upper
projecting portion 42 and a lower projecting portion 44 that
protrude from the front of the automobile. The bumper cover 46 is
disposed so that the upper projecting portion 42 is placed at a
height such as to come into contact with the knee of a pedestrian
when the bumper cover 46 collides with the pedestrian, and so that
the lower projecting portion 44 is placed at a height such as to
come into contact with a portion near the shank of the pedestrian
(see FIG. 5). In this position, the bumper cover 46 is mounted, for
example, by being fixed to a front grille 48, which forms a front
face of the automobile, by bolts. In FIG. 4, reference numerals 50
and 51 denote a bonnet and a radiator, respectively.
[0079] A bumper reinforcement 52 made of a rigid member is fixed
inside the upper projecting portion 42 of the bumper cover 46 that
is thus mounted at the front of the automobile (offset rearward
from the front of the automobile). The bumper reinforcement 52
faces an inner surface of the upper projecting portion 42 with a
predetermined space therebetween, and extends in the width
direction of the automobile. Further, a shock-absorbing member 54
is fixed to the bumper reinforcement 52 between the bumper
reinforcement 52 and the upper projecting portion 42 of the bumper
cover 46. The shock-absorbing member 54 is configured in a known
manner, and has a thin resin body 56 that is shaped like a square
pillar, which has a trapezoidal shape taken in a plane parallel to
the impact-receiving direction and closed at one side, and is less
rigid than the leg sweep member 10.
[0080] The front section 26 of the base plate 12 in the leg sweep
member 10 is disposed inside the lower projecting portion 44 of the
bumper cover 46, and an upper surface of a rear portion of the rear
section 28 is in contact with a lower surface of a radiator support
58 that extends in the widthwise direction of the automobile and is
fixed to the front of the automobile so as to support the radiator
51. Resin clips 62 extending through an inward flange 60 integrally
provided with a lower end of the lower projecting portion 44 are
fitted in the corresponding through-holes 36 provided in the front
end and the side ends of the front section 26 of the base plate 12,
and the front section 26 is thereby fixed to the inward flange 60.
Also, each of fixing bolts 64 are fitted in the corresponding one
of through-holes 38 at the rear end of the rear section 28, and the
rear section 28 is thereby fixed to the radiator support 58.
[0081] Accordingly, the leg sweep member 10 horizontally extends in
the longitudinal direction of the automobile inside the lower
projecting portion 44 of the bumper cover 46, and connects the
lower projecting portion 44 and the radiator support 58 while the
front section 26 of the base plate 12 protrudes from the front of
the automobile. While the base plate 12 is fixed to the bumper
cover 46 and the radiator support 58 by the resin clips 62 and the
fixing bolts 64 in this embodiment, the fixing manner is not
limited thereto, and other known fixing structures may be adopted
appropriately. For example, when the rear section 28 of the base
plate 12 is reliably to the radiator support 58, the front section
26 does not always need to be fixed to the bumper cover 46.
[0082] As shown in FIG. 5, when the bumper cover 46 of the front
bumper 40 comes into contact with or collides with a leg portion 66
of a pedestrian, the upper projecting portion 42 and the lower
projecting portion 44 of the bumper cover 46 are deformed
(displaced) toward the rear of the automobile by a shock due to the
contact with portions of the leg portion 66 near a knee 68 and a
shank 70, and the shock-absorbing member 54 and the leg sweep
member 10 respectively provided inside the upper and lower
projecting portions 42 and 44 are also deformed (displaced)
rearward. In this case, since the shock-absorbing member 54 (resin
body 56) is less rigid than the leg sweep member 10, the
shock-absorbing member 54 is deformed more than the leg sweep
member 10. Consequently, the lower projecting portion 44 of the
bumper cover 46 protrudes more from the front of the automobile
than the upper projecting portion 42, and a reaction force to an
impact load caused by the collision between the leg portion 66 and
the bumper cover 46 acts the portion of the leg portion 66 near the
shank 70 via the lower projecting portion 44. As a result, the
portion of the leg portion 66 near the shank 70 is swept away
(tripped) by the leg sweep member 10 so that the pedestrian falls
down onto the bonnet 50 of the automobile. This reduces bending of
the knee 68 of the pedestrian in an undesired direction, and
minimizes injury, such as bone fracture, of the knee 68. In this
way, protection and safety of the pedestrian are achieved
effectively.
[0083] Particularly when the leg sweep member 10 of the first
embodiment is deformed by a shock inputted in a collision between
the leg portion 66 and the bumper cover 46 of the front bumper 40,
stress concentration is caused at a boundary portion 72 between the
rear section 28 having the lowest rigidity and the center section
30 which is less rigid than the front section 26 and more rigid
than the rear section 28, and at a front adjacent portion 74
provided on the front side of and adjacent to a portion of the rear
section 28 fixed to the radiator support 58 (more specifically, a
portion of the rear section 28 that is provided on the front side
of the through-holes 38 and in contact with outer peripheries of
washers 77 which are brought into engagement with the peripheral
portions of the fixing bolts 64). By the stress concentration, the
base plate 12 is bent (buckled) at two positions, namely, at the
boundary portion 72 and the front adjacent portion 74. As a result,
overall the base plate 12 (leg sweep member 10) is deformed in an
approximate S-shape or a staircase shape.
[0084] As a result, in this leg sweep member 10, the impact load is
rapidly increased in the early stage of the shock input. Therefore,
the maximum value of the impact load inputted by the collision
between the leg portion 66 and the bumper cover 46 speedily and
reliably reaches a target value, and a sufficient reaction force to
the impact load is ensured reliably.
[0085] Accordingly, when the bumper cover 46 collides with the leg
portion 66 of the pedestrian, a sufficient reaction force to the
inputted impact load acts on the leg portion 66, and the leg
portion 66 is reliably swept away. Therefore, the leg portion 66 is
reliably protected at a higher level.
[0086] As described above, when the bumper cover 46 of the front
bumper 40 fixed to the automobile comes into contact with or
collides with the leg portion 66 in a state in which the leg sweep
member 10 is disposed inside the bumper cover 46, the base plate 12
is bent at two positions, that is, at the boundary portion 72
between the center and rear sections 30, 28, and the front adjacent
portion 74 provided on the front side of and adjacent to the
portion of the rear section 28 fixed to the radiator support 58.
Therefore, the impact load inputted to the entire leg sweep member
10 is rapidly increased in the early stage of the input. The
maximum value of the impact load greatly depends on the flexural
rigidities of the boundary portion 72 and the front adjacent
portion 74 of the base plate 12. That is, the maximum value of the
impact load is large when the flexural rigidities of the boundary
portion 72 and the front adjacent portion 74 are high, and is small
when the flexural rigidities are low.
[0087] FIG. 6 shows a leg sweep member 10 according to a second
embodiment of the present invention. In the second embodiment, the
distance D.sub.4 between the boundary portion 72 and the front
adjacent portion 74 is increased by decreasing the dimension
D.sub.2 of the center section 30 of the base plate 12 in the depth
direction and increasing the dimension D.sub.3 of the rear section
28 in the depth direction without changing the dimension D.sub.1 of
the front section 26 of the base plate 12 in the depth direction.
In this case, when the bumper cover 46 collides with the leg
portion 66 of the pedestrian, the base plate 12 is easily bent at
the boundary portion 72 and the front adjacent portion 74 on the
principle of leverage, as shown in FIG. 7. Consequently, the
maximum value of an impact load inputted in a collision between the
leg portion 66 and the bumper cover 46 can be favorably made small.
Materials and components of the leg sweep member 10 shown in FIGS.
6 and 7, and leg sweep members shown in FIGS. 8 to 11, which will
be described below, similar to those of the leg sweep member 10
shown in FIGS. 1 to 5 are denoted by the same reference numerals,
and detailed descriptions thereof are omitted.
[0088] In this way, in the leg sweep member 10 of the second
embodiment, the maximum value of the impact load can be arbitrarily
changed and the load characteristic can be easily tuned by an
extremely simple design change, that is, by simply increasing or
decreasing the dimension of the center section 30 of the base plate
12 in the depth direction.
[0089] Therefore, it is possible to easily and reliably optimize
the load characteristic that is required, for example, depending on
the shape and inner space of the bumper cover 46 of the front
bumper 40 or the configuration of the shock-absorbing member 54
disposed inside the upper projecting portion 42 of the bumper cover
46. Accordingly, a reaction force to the impact load caused in a
collision between the leg portion 66 of the pedestrian and the
front bumper 40 can sufficiently act on the leg portion 66,
regardless of the type of the automobile in which the leg sweep
member 10 is installed. As a result, the leg portion 66 can be more
reliably and more stably swept away, and can be more sufficiently
protected.
[0090] FIG. 8 shows a leg sweep member 10 according to a third
embodiment of the present invention. In the third embodiment, the
dimensions D.sub.1, D.sub.2, and D.sub.3 of the front section 26,
the center section 30, and the rear section 28 of the base plate 12
in the longitudinal direction are not changed, and a reinforcing
plate 76 having a predetermined flexural rigidity and made of
synthetic resin is fixed to an upper or lower surface of the base
plate 12 so as to extend over the boundary portion 72 and the front
adjacent portion 74.
[0091] In this case, the flexural rigidities of the boundary
portion 72 and the front adjacent portion 74 are made higher than
when the reinforcing plate 76 is not fixed. Therefore, the maximum
value of the impact load inputted by a collision between the leg
portion 66 of the pedestrian and the bumper cover 46 can be
effectively increased, depending on the flexural rigidity of the
reinforcing plate 76. As is evident from the above, the reinforcing
plate 76 forms a first reinforcing member and a second reinforcing
member. Even when the flexural rigidities of the boundary portion
72 and the front adjacent portion 74 are thus increased by the
reinforcing plate 76, the base plate 12 is, of course, structured
so that the rigidity thereof becomes higher in the order of the
rear section 28, the center section 30, and the front section
26.
[0092] In the leg sweep member 10 having the above-described
configuration, the maximum value of the impact load can be
arbitrarily changed and the load characteristic can be easily tuned
by an extremely simple design change, that is, by simply fixing any
of the reinforcing plate 76 having a different flexural rigidity
onto the upper or lower surface of the base plate 12. As a result,
the above-described operations and advantages can be achieved
effectively.
[0093] While the single reinforcing plate 76 is fixed to the base
plate 12 so as to extend over the boundary portion 72 and the front
adjacent portion 74 in the third embodiment, for example, two
reinforcing plates having the same or mutually different
rigidities, or two reinforcing members having such rigidities and
each made of a material other than the plate, may be respectively
fixed as first and second reinforcing members to the boundary
portion 72 and the front adjacent portion 74 in order to change the
rigidities of the boundary portion 72 and the front adjacent
portion 74.
[0094] While the embodiments of the present invention have been
described in detail above, it should be noted that these
embodiments are just exemplary, and that the scope of the present
invention is not limited by the embodiments.
[0095] For example, while the rigidities of the front section 26,
the center section 30, and the rear section 28 of the base plate 12
are made different, depending on whether the ribs 16 to 24 are
provided, and the number and positions of the ribs 16 and 24 in the
above embodiments, the structure for making the rigidities
different are not particularly limited as long as the rigidity of
the base plate 12 becomes lower in the order of the front section
26, the center section 30, and the rear section 28.
[0096] Therefore, for example, plate-shaped thick and flat ribs may
protrude integrally from the front section 26, and the same number
of plate-shaped thin and flat ribs as that of the ribs on the front
section 26 may protrude integrally from the center section 30. In
this case, the rigidity of the base plate 12 can also become lower
in the order of the front section 26, the center section 30, and
the rear section 28.
[0097] FIG. 9 shows a leg sweep member 10 according to a fourth
embodiment of the present invention. In the fourth embodiment, the
ribs 16 to 24 are removed from the front section 26 and the center
section 30. In this case, a first plate-shaped reinforcing member
78 having a predetermined thickness is fixed on the entirety of one
surface of the center section 30, and a second plate-shaped
reinforcing member 80 is fixed on the entirety of one surface of
the front section 26. The thickness and rigidity of the second
plate-shaped reinforcing member 80 are larger than those of the
first plate-shaped reinforcing member 78. This also allows the
rigidity of the base plate 12 to become lower in the order of the
front section 26, the center section 30, and the rear section
28.
[0098] In this case, the materials of the first plate-shaped
reinforcing member 78 and the second plate-shaped reinforcing
member 80 are not particularly limited. Further, the first
plate-shaped reinforcing member 78 may be fixed on both surfaces of
the center section 30, and the second plate-shaped reinforcing
member 80 may be fixed on both surfaces of the front section 26.
Alternatively, the first plate-shaped reinforcing member 78 and the
second plate-shaped reinforcing member 80 may be fixed on the other
surfaces of the sections. Through-holes 82 are provided in the
second plate-shaped reinforcing member 80 fixed on the front
section 26. The through-holes 82 are provided corresponding to and
coaxially with the through-holes 36 in the front section 26, and
have the same shape and size as those of the through-holes 36.
[0099] FIG. 10 shows a leg sweep member 10 according to a fifth
embodiment of the present invention. In the fifth embodiment,
instead of forming the ribs 16 to 24 on the front section 26 and
the center section 30 of the base plate 12 or fixing the
reinforcing plates 78 and 80 having mutually different rigidities
thereon, the thickness of the base plate 12 is made different among
the sections, that is, so that the thickness becomes smaller in the
order of the front section 26, the center section 30, and the rear
section 28. This also allows the rigidity of the base plate 12 to
become lower in the order of the front section 26, the center
section 30, and the rear section 28.
[0100] While the center section 30 of the base plate 12 has a
uniform rigidity in the above embodiments, a plurality of areas
having mutually different rigidities may be provided in the center
section 30 so as to extend over the full dimension in the breadth
direction, to adjoin in the depth direction, and to be arranged in
decreasing order of the rigidities from a front side of the center
section.
[0101] FIG. 11 shows a leg sweep member 10 according to a sixth
embodiment of the present invention. In the sixth embodiment, the
center section 30 is further divided into two areas, that is, a
front center area 84 and a rear center area 86. A plurality of
first ribs 16 and a third rib 18, and a plurality of first
auxiliary ribs 32 and a second auxiliary rib 34 respectively
protrude on the upper surface and the lower surface of the front
center area 84 so that the front center area 84 is less rigid than
the front section 26 and more rigid than the rear section 28. On
the other hand, the rear center area 86 is made thick so that the
center area 86 is less rigid than the front center area 84 and is
more rigid than the rear section 28.
[0102] In the leg sweep member 10 having the above-described
configuration, the base plate 12 is bent and deformed not only at
the boundary portion 72 and the front adjacent portion 74, but also
at a boundary portion between the front and rear center areas 84,
86 of the center section 30, depending on the volume of the shock
applied in a collision between the leg portion 66 of the pedestrian
and the front of the automobile (for example, the front bumper 40).
This advantageously suppresses an excessive increase in the impact
load in the early stage of the input of the shock.
[0103] When such portions having mutually different rigidities are
provided in the center section 30 of the base plate 12, the number
of the portions may be three or more.
[0104] Further, when some portions having mutually different
rigidities are thus provided in the center section 30, for example,
various types of ribs may be provided in the sections in different
numbers or with different thicknesses, reinforcing members having
different thicknesses may be fixed to the portions, or the portions
may have different thicknesses. These structures may be
appropriately adopted in combination.
[0105] In addition, the present invention is advantageously applied
not only to the pedestrian protection apparatus installed inside
the bumper fixed at the front of the automobile, but also to a
pedestrian protection apparatus installed at the front of the
automobile independently of the bumper, and pedestrian protection
apparatuses that are installed in various manners at the fronts of
vehicles other than the automobile.
[0106] While the specific embodiments of the present invention have
been described in detail above, the embodiments are just exemplary,
and the present invention can be carried out in other various
manners. It is to be understood that the present invention is not
limited to the foregoing description, but may be embodied with
various changes, modifications and improvements that may occur to
those skilled in the art, without departing from the scope of the
invention defined in the attached claims.
EXAMPLES
[0107] Representative examples of the present invention will be
described below in order to more clearly specify the
characteristics of the invention. It should be noted that the
present invention is not limited to the description of the
examples.
Example 1
[0108] A leg sweep member serving as a first invention example
having a configuration according to the present invention was
formed and prepared by ejection molding using polypropylene. In
this leg sweep member, the thickness and rigidity of a base plate
become smaller in the order of a front section, a center section,
and a rear section thereof, as shown in FIG. 10. The total
dimension of the base plate in the depth direction is 200 mm, and
the dimensions of the front section, the center section, and the
rear section of the base plate are 50 mm, 100 mm, and 50 mm,
respectively. The thicknesses of the front section, the center
section, and the rear section are 3.0 mm, 2.5 mm, and 2.0 mm,
respectively.
[0109] For comparison, a leg sweep member serving as a first
comparative example was formed and prepared by ejection molding
using polypropylene. In the first comparative example, the
thicknesses of a front section, a center section, and a rear
section of a base plate are 2.0 mm, 2.5 mm, and 3.0 mm,
respectively. That is, the thickness of the base plate becomes
larger in the order of the front section, the center section, and
the rear section thereof so that the rigidity of the base plate
becomes higher in the order of the front section, the center
section, and the rear section thereof.
[0110] A leg sweep member serving as a second comparative example
was also formed and prepared by ejection molding using
polypropylene. In the second comparative example, the thicknesses
of a center section, a rear section, and a front section of a base
plate are 3.0 mm, 2.5 mm, and 1.5 mm, respectively, so that the
rigidity of the base plate becomes lower in the order of the center
section, the rear section, and the front section thereof. Moreover,
a leg sweep member serving as a third comparative example was
formed and prepared by ejection molding using polypropylene. In the
third comparative example, a base plate has a uniform thickness of
2.5 mm, and has a uniform rigidity.
[0111] In the manner shown in FIG. 4, the prepared leg sweep
members having different structures, that is, the first invention
example and the first to third comparative examples were
respectively mounted inside bumper covers of front bumpers fixed at
the fronts of actual vehicles (automobiles), thereby obtaining four
types of test vehicles. Subsequently, a pedestrian collision test
was conducted on each of the test vehicles on the assumption that
the front bumper of the test vehicle collided with a pedestrian,
and it was checked in a known manner how the impact load inputted
to each of the leg sweep members changed with time. FIG. 12 shows
the test results. In the pedestrian collision test for each test
vehicle, the front of the front bumper of the test vehicle was
caused to collide with a dummy having a weight of 14 kg at a speed
of 40 km/h.
[0112] As shown in FIG. 12, in the leg sweep member of the first
invention example, the impact load rapidly increased in the early
stage of the input of the shock by the collision with the
pedestrian, and instantaneously reached a target load after the
collision. In contrast, in the leg sweep members of the first to
third comparative examples, the impact load slowly increased in the
early stage of the shock input, and reached the target load a
relatively long time after the collision, or did not reach the
target load. This clearly shows that a reaction force to the impact
load can be sufficiently and reliably ensured in the leg sweep
member having the structure according to the present invention.
Example 2
[0113] A leg sweep member having a configuration according to the
present invention shown in FIGS. 1 to 3 was formed and prepared as
a second invention example by ejection molding using polypropylene.
In the second invention example, the rigidity of a base plate
becomes lower in the order of a front section, a center section,
and a rear section because of first to fifth ribs provided on the
front section and the center section. The total dimension of the
base plate in the depth direction is 190 mm, and the dimensions of
the front section, the center section, and the rear section of the
base are 30 mm, 110 mm, and 50 mm, respectively. The each of the
first to fifth ribs provided on the front section and the center
section is 3 mm in thickness, and are 25 mm in height.
[0114] In addition, a leg sweep member having a configuration
according to the present invention was formed and prepared as a
third invention example. The third invention example has the same
basic structure as that of the above-described second invention
example. The dimensions of a front section, a center section, and a
rear section of a base plate in the depth direction are 30 mm, 130
mm, and 30 mm, respectively. The dimension of the base plate in the
depth direction and the dimension of the front section in the depth
direction are equal to those in the second invention example, but
the dimension of the center section is larger and the dimension of
the rear section is smaller than in the second invention
example.
[0115] In a manner similar to that for the first example, the leg
sweep members of the second and third invention examples thus
prepared and having different configurations were installed at the
fronts of actual vehicles (automobiles), thereby obtaining
two-types of test vehicles. A pedestrian collision test similar to
that for the first example was conducted on each of the test
vehicles, and it was checked in a known manner how the impact load
inputted to the leg sweep member in a collision with the pedestrian
changed with time. FIG. 13 shows the test results.
[0116] As shown in FIG. 13, the maximum value of the impact load in
the leg sweep member of the third invention example, in which the
center section of the base plate is longer in the depth direction,
is larger than that of the leg sweep member of the second invention
example in which the dimension of the center section in the depth
direction is shorter. This clearly shows that the load
characteristic of the leg sweep member can be easily tuned by
changing the dimension in the depth direction of the center section
whose rigidity is between the rigidities of the front section and
the rear section, and thereby adjusting the distance between the
boundary portion between the center section and the rear section,
and the front adjacent portion on the front side of and adjacent to
the portion of the rear section fixed to the vehicle.
Example 3
[0117] First, the leg sweep member of the second invention example
in the above-described second example was prepared. In addition, a
fourth invention example having a configuration according to the
present invention shown in FIG. 8, and having a basic structure
similar to that of the second invention example was prepared. In
the leg sweep member of the fourth invention example, an iron
reinforcing plate having a predetermined flexural rigidity is fixed
on a lower surface of a base plate so as to extend over a boundary
portion and a front adjacent portion. The reinforcing plate has a
thickness of 1.0 mm, and a dimension of 80 mm in the depth
direction.
[0118] In a manner similar to that for the above-described first
example, the two-types of leg sweep members of the second and
fourth invention examples were installed at the fronts of actual
vehicles (automobiles) to obtain two-types of test vehicles.
Subsequently, a pedestrian collision test similar to that for the
first example was conducted on each of the test vehicles, and it
was checked in a known manner how the impact load inputted to the
leg sweep member in a collision with a pedestrian changed with
time. FIG. 14 shows the test results.
[0119] As show in FIG. 14, the maximum value of the impact load in
the leg sweep member of the fourth invention example, in which the
reinforcing plate is fixed on the lower surface of the base so as
to extend over the boundary portion and the front adjacent portion,
is larger than that in the leg sweep member of the second invention
example in which the reinforcing plate is not provided. This
clearly shows that the load characteristic of the leg sweep member
can also be easily tuned by fixing the reinforcing plate on the
lower surface of the base so as to extend over the boundary portion
and the front adjacent portion.
Example 4
[0120] First, the leg sweep member of the second invention example
in the above-described second example was prepared. In addition, a
leg sweep member having a basic structure similar to that of the
second invention example was prepared as a fifth invention example.
In the fifth invention example, separately from first and second
ribs provided on a front section and a center section of a base
plate, a reinforcing rib protrudes integrally from a lower surface
of the base plate so as to extend over a boundary portion and a
front adjacent portion. The dimension of the reinforcing rib in the
depth direction is 80 mm, and the thickness thereof is 1.0 mm. By
forming this reinforcing rib, the rigidities of the front, center,
and rear sections of the base are stably balanced so that the
rigidity of the base plate becomes lower in the order of the front
section, the center section, and the rear section.
[0121] In a manner similar to that for the above-described first
example, the two-types of leg sweep members of the second and fifth
invention examples were installed at the fronts of actual vehicles
(automobiles) to obtain two-types of test vehicles. Subsequently, a
pedestrian collision test similar to that in the first example was
conducted on each of the test vehicles, and it was checked in a
known manner how the impact load inputted to the leg sweep member
in a collision with a pedestrian changed with time. FIG. 15 shows
the test results.
[0122] As shown in FIG. 15, the maximum value of the impact load in
the leg sweep member of the fifth invention example, in which the
reinforcing rib is provided integrally with the lower surface of
the base plate so as to extend over the boundary portion and the
front adjacent portion, is larger than that in the leg sweep member
of the second invention example in which the reinforcing rib is not
provided. This clearly shows that the load characteristic of the
leg sweep member can also be easily tuned by forming the
reinforcing rib integrally with the lower surface of the base so as
to extend over the boundary portion and the front adjacent
portion.
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